Osteomalacia is an end-stage bone disease of chronic and severe vitamin D or phosphate depletion of any cause. Its importance has increased because of the rising incidence of vitamin D deficiency. Yet, not all cases of osteomalacia are cured by vitamin D replacement, and furthermore, not all individuals with vitamin D deficiency develop osteomalacia. Although in the past osteomalacia was commonly caused by malabsorption, nutritional deficiency now is more common. In addition, recent literature suggests that nutritional vitamin D deficiency osteomalacia follows various bariatric surgeries for morbid obesity. Bone pain, tenderness, muscle weakness, and difficulty walking are all common clinical manifestations of osteomalacia. Diagnostic work-up involves biochemical assessment of vitamin D status and may also include a transiliac bone biopsy. Treatment is based on aggressive vitamin D repletion in most cases with follow-up biopsies if patients are started on antiresorptive or anabolic agents.